Tattoo pen



FIG. 1 is a top front perspective view of the tattoo pen showing my new design;

FIG. 2 is a bottom back perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a back view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a left side view thereof;

FIG. 7 is a top view thereof; and,

FIG. 8 is a bottom view thereof.

The broken lines depict portions of the tattoo pen that form no part of the claimed design. 

CLAIM The ornamental design for a tattoo pen, as shown and described. 